CLI 



CLO 



true strata or layers of deposition. The 

 planes of cleavage are, therefore, distin- 

 guishable from those of stratification. 



CLEA'VLANDITE. A mineral for- 

 merly ranked among felspars, but differ- 

 ing in this, that the 13 or 14 per cent, 

 of potash in felspar is replaced by about 

 10 per cent, of soda in the cleavland- 

 ite.— Ure. 



CLEF. The French term for a key. 

 In music, it is a symbol placed at the 

 beginning of the staff to determine the 

 names of the lines and spaces, and the 

 character of each note. 1. The treble 

 clef is placed on the second line, to which 

 it gives the name of G. 2. The mean 

 clef gives the name of C to any line on 

 •which it is placed. It is called the so- 

 prano clef when placed on the first line; 

 the mezzo soprano, when on the second; 

 the alto, contratenor, or countertenor, 

 when on the third ; and the tenor, when 

 on the fourth. 3. The base clef is placed 

 on the fourth line, to which it gives the 

 name of F. 



CLEPSY'DRA {KKe^fvhpa, from KXeTTToy, 

 to steal, v8<ap, water). A water-clock, 

 made somewhat like our sand-glasses, 

 with a narrow orifice through which the 

 water trickled slowly, used by the Greeks 

 to time speeches in the law-courts. This 

 instrument was commonly employed by 

 astronomers for the measurement of 

 time before the invention of clocks and 

 watches. 



CLE'RID^. A family of Coleopterous 

 insects, of the section Malacodermi, 

 named from the genus Clerus. 



CLIMACTE'RIC {KXinaKTijP, the step 

 of a ladder). The progression of the life 

 of man. It is usually divided into pe- 

 riods of seven years ; the ninth period, 

 or 63rd year, being the grand climac- 

 teric. 



CLI'MATE [KXi/jia, inclination). A 

 term applied in its popular sense to the 

 state of the air, in order to express the 

 particular combination of temperature 

 and moisture, which exists in the atmo- 

 sphere of any given country. 



In its geographical and technical appli- 

 cation. Climate, or Clime, denotes an 

 imaginary narrow belt of the globe, paral- 

 lel to the equator; and is so called be- 

 cause the difference of climates depends 

 on the inclination, or obliquity of the 

 sphere. The belts constituting the seve- 

 ral climates are small, depending on the 

 average length of the longest day : that 

 of each increasing by half an hour, from 

 the equator to the polar circles, when the 

 81 



climates are counted by months, till they 

 reach the poles, 



CLI'MAX (xAIyuaf , a ladder or stair- 

 case). In rhetoric, a gradual ascent from 

 weaker to stronger expressions, as in the 

 celebrated *' gradatio " of Cicero, — abiit, 

 excessit, evasit, erupit. 



CLINA'NTHIUM {kXIvco, to incline, 

 avOof, a flower). A term applied by some 

 botanical writers to the receptacle of com- 

 positae which is not fleshy, but is sur- 

 rounded by an involucrum. By other 

 writers, this part is called thalamus and 

 phoranthium. 



CLINKER. Black oxide of iron, or 

 the oxidum ferroso-ferricum of Berzelius. 

 It is always formed when iron is heated to 

 redness in the open air, and is therefore 

 readily obtained at the blacksmith's 

 forge. 



CLINKSTONE. Ahardfelspathicrock, 

 named from the sharp noise which it 

 emits when struck with the hammer; 

 its fracture is splintery and conchoidal, 

 its lustre glistening, its colours various, 

 often with veins of jasper. 



CLINO'METER {kXivu}, to incline, 

 nirpov, a measure). A quadrant adapted 

 for showing the inclination of strata in 

 geological operations. 



CLIO'NIDiE. The Clio tribe; a fa- 

 mily of naked marine mollusca, the first 

 order of Cuvier's Pteropods. 



CLOA'CA (a sewer). A receptacle 

 observed in the monotremata, in birds, 

 in reptiles, and in many fishes, which 

 receives the faeces and the urine, to- 

 gether with the semen of the male, and 

 the ovum of the female. 



CLOCK. A well known machine for 

 measuring time, regulated by the uni- 

 form motion of a pendulum. Common 

 clocks are made to show mean solar 

 time, but those used at observatories, for 

 the purpose of observing the time of the 

 stars transiting the meridian, show side- 

 real time. 



CLOUDS. Masses of visible aqueous 

 vapour, which float in the sky, or drift 

 through it with the wind, at different 

 elevations, assuming every variety of 

 colour and form. They have been clas- 

 sified by Howard under three primary 

 forms, and four modifications. 



1. Primary Forms. These are the cir- 

 rus, or curl-cloud, composed of fibrous 

 stripes, which are parallel, flexuous, or 

 diverging, and extensible in all direc- 

 tions ; the cumulus, or stacken-cloud, 

 heaped together in convex or conical 

 masses, and increasing upwards from a 

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